The 6GW8 was one of the last audio triode output pentode valves designed. Uses were in domestic radio and audio equipment. Normally in single ended output stages for radiograms and tape recorders. The design proved popular in low cost stereo systems and was made by several companies, this exhibit being made by Westinghouse.
Copper grid supports are used for better heat dissipation.
The triode section in the foreground with the larger pentode behind.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 69 mm tall.
References: Datasheet & 1040. Type 6GW8 was first introduced in 1961.